1. Field of the Invention
The present invention relates to a disk braking device in which a disk plate fixed to a wheel is interposed by friction members, and a motorcycle provided with the disk braking device.
2. Description of Related Art
In a conventional disk braking device for motorcycles, the number of pistons may be increased to increase braking effective diameter and braking force. Also, to make the piston pushing force uniform, the pistons at an entering side of a disk plate may be smaller in cylinder area than a leaving side (see, for example, JP-A-5-116668).
When the number of pistons is increased, a pad unit must also be lengthened in circumferential dimension corresponding to the increase in number of pistons. Consequently, the friction members of the pad unit may warp due to frictional heat or the like and become nonuniform in bearing against a disk plate, causing a deterioration in reaction at the time of braking.
In order to suppress warp of the friction members and dispersion in bearing, the pad unit may be divided into a number of sections corresponding to the number of pistons. However, division of the pad unit causes a problem that the caliper must be larger and the service life of the friction members becomes non-uniform.